(1) Field of the Invention
The present invention pertains to a motorized conveyor pulley of the type comprising a cylindrical pulley drum with axially opposite end plates enclosing an electric motor and a drive transmission within the drum. The end plates of the pulley are mounted on a pair of shaft ends that pass through the end plates at the axially opposite ends of the pulley and support the motor and drive transmission in the pulley as well as supporting the pulley drum housing for rotation. As well as the motor and transmission, the pulley drum housing also contains an amount of lubricant that lubricates the bearings and gears of the drive transmission and cools the motor. In particular, the present invention pertains to a passive lubrication collector and manager that is mounted in the pulley drum housing and wipes lubricant from the interior surface of the pulley drum housing and then directs the wiped lubricant to the bearings and gears of the drive transmission. The passive lubrication collector and manager enables using a smaller amount of lubricant contained in the pulley drum housing than prior art pulley drums and also enables the use of less expensive sleeve bearings instead of ball and/or roller bearings employed in the prior art conveyor pulleys, thereby significantly decreasing the costs of manufacturing the conveyor pulley. The passive lubrication collector and manager is also used in combination with journal collars that support the journal ends of shafts of the drive transmission where the journal collars have openings that are fed with lubricant by the lubrication collector and manager, enabling use of the less expensive sleeve bearings instead of ball and/or roller bearings.
(2) Description of the Related Art
The motorized conveyor pulley of the type of which the present invention is an improvement is employed at one end of a flat, continuous belt conveyor where the belt of the conveyor is looped or wrapped over the pulley drum housing of the motorized conveyor pulley at one end of the conveyor and is wrapped over an idler pulley at an opposite end of the conveyor. In order to provide sufficient friction engagement between the pair of pulleys and the belt to avoid slipping of the belt on the pulleys when the belt is conveying a substantial load, the belt is usually stretched very tight between the pair of pulleys resulting in a substantial load exerted on the pulleys by the belt.
The load exerted by the belt on the motorized conveyor pulley is transferred to the component parts contained inside the pulley. The typical motorized conveyor pulley includes a cylindrical pulley drum housing having a hollow interior. A pair of circular end plates close off the axially opposite ends of the drum housing. The end plates have coaxial center bores and stationary stub shafts extend through the center bores. Each stub shaft has a bearing and seal mounted on its exterior that is received in the center bore of one of the end plates, thereby mounting the pulley drum for rotation on the stationary stub shafts.
Contained inside the pulley drum is an electric motor and a drive transmission. The electric motor and a gear carrier of the drive transmission are mounted stationary to the ends of the two stub shafts projecting into the interior of the pulley drum housing. The electric wiring of the motor typically passes through a hole in one of the end shields of the motor and then through a hole in the gear carrier into the gear carrier interior. The wiring then passes through a center bore of the shaft on which the gear carrier is mounted to the exterior of the conveyor pulley. The electric motor drives the gear transmission mounted on the gear carrier that in turn drives a ring gear mounted to the interior surface of the pulley drum housing, thereby rotating the pulley. The journal ends of the shafts of the gear transmission are typically mounted in ball bearings or roller bearings due to the substantial loads exerted on the shaft ends.
The pulley drum contains a bath of lubricant, usually an expensive synthetic lubricant, that at times fills half the interior volume of the pulley drum housing. The lubricant both cools and lubricates the motor, the transmission gearing and the bearings finding its way into the spaces between the balls and rollers of the bearings. It is necessary that the pulley drum housing contain a substantial amount of lubricant in order to reach all of the gears and bearings of the drive transmission. The large amount of lubricant is needed because when the conveyor pulley is operated, usually at 100 rpm, the rotation of the pulley drum housing will cause a large portion of the lubricant to collect around the inner surface of the pulley drum housing due to the centrifugal force exerted on the lubricant by the rotation of the conveyor pulley. This decreases the level of the portion of lubricant accumulated at the bottom of the interior of the pulley drum housing. Therefore, to ensure that the lubricant reaches the gears and bearings of the drive transmission as the conveyor pulley is operated, a substantial amount of lubricant is contained in the pulley drum housing.
The substantial amount of lubricant contained in the pulley drum housing contributes significantly to the overall cost of the pulley conveyor. Depending on the size of the pulley conveyor, at times the amount of the synthetic lubricant contained inside the pulley conveyor is the most expensive component part of the pulley conveyor construction. In addition, because a substantial amount of lubricant must be contained in the pulley drum housing, there is an increased opportunity for the lubricant to leak from the pulley drum housing along the electric lead lines of the motor as they pass from the motor, through the gear carrier and one of the stub shafts of the conveyor pulley.
The construction of the typical conveyor pulley could be improved by reducing the amount of lubricant required to be contained in the pulley drum housing and thereby reducing its costs and likelihood of leaking from the pulley drum housing while still ensuring that adequate amounts of lubricant are supplied to the bearings and the gears of the drive transmission.
The motorized conveyor pulley of the invention overcomes the disadvantages associated with prior art conveyor pulleys by providing the conveyor pulley with a passive lubrication collector and manager that enables a significant reduction in the amount of synthetic lubricant employed in the conveyor pulley drum housing. In addition, through use of the lubrication collector and manager the ball and roller bearings that support the shafts of the drive transmission may be replaced with less expensive sleeve bearings due to the construction of the collector and manager and due to novel collars of the conveyor pulley drive transmission that support the sleeve bearings and the shaft journal ends. By reducing the amount of synthetic lubricant required by the motorized conveyor pulley and replacing the roller bearings and ball bearings of the drive transmission with sleeve bearings, the cost of the motorized conveyor pulley of the present invention is substantially reduced.
The passive lubrication collector and manager of the invention is basically a cover that is mounted inside the conveyor pulley drum over the electrical wiring exiting the motor as well as the drive transmission. By projecting over the wiring of the electric motor, the cover directs splashing lubricant away from the wiring and reduces the likelihood of lubricant splashing onto the wiring as the conveyor pulley is operated and then potentially leaking along the wiring out of the conveyor pulley. A wiper is mounted on the cover and projects upwardly from the cover and engages in sliding engagement with the interior surface of the conveyor pulley drum housing. The wiper wipes lubricant from the interior surface of the conveyor pulley drum housing as the conveyor pulley is operated and directs the lubricant downwardly onto the top surface of the cover. The cover has a crest at its middle and lower edges with gutters on opposite sides of the crest. The crested cover directs lubricant downwardly toward the gutters where the lubricant is collected. The gutters communicate with lubricant guides that direct portions of the lubricant gravitating downwardly along the guides to the bearings and the gears of the drive transmission. In addition, collars mounting the journal ends of the drive shafts of the drive transmission in the motor end shield and on the gear carrier have openings providing access to the journal ends of the shafts in the collars. The lubricant guides direct gravitating lubricant to the openings of the collars, thereby ensuring an adequate supply of lubricant to the journal ends of the shafts. This direct supply of lubricant to the journal ends of the shafts enables the ball bearings and roller bearings of the prior art conveyor pulley to be replaced with less expensive sleeve bearings. Thus, the passive lubricant collector and manager and the redesigned bearing collars of the conveyor pulley of the invention reduce the manufacturing costs of a conveyor pulley over that of prior art conveyor pulleys by enabling the amount of synthetic lubricant employed in the conveyor pulley to be significantly reduced and by enabling the use of less expensive sleeve bearings for the drive transmission shafts than the ball and roller bearings of the prior art.